Jaw plate for jaw crushers



4, 1956 A. J. ROUBAL JAW PLATE FOR JAW CRUSHERS Filed July 8, 1952United States Patent JAW PL'ATE FOR JAW CRUSHERS Alexander J. Roubal,Milwaukee, Wis., assignor to Allis- Chalmers Manufacturing Company,Milwaukee, Wis.

Application July 8, 1952, Serial No. 297,596 4 Claims. (Cl. 241291) Thisinvention relates to an improvement in jaw plates of the kind utilizedfor the movable and stationary jaws of jaw crushers.

Jaw plates are customarily made of hard, tough steel, such as manganesesteel, which in operation may become deformed by repeated impacts of therock or other material being crushed. The metal at the working surfaceof the plate is peened by the impacting of the material being crushed insuch a manner that the surface layer tends to expand laterally by coldworking action. Lateral expansion of the working surface in prior artjaw plates causes the plates to warp in that the metal at the rearsurface of the plate, which is not subjected to a peening action, doesnot expand laterally. This expansion of the working surface, withoutcorresponding expansion of the rear surface, causes a deformation orwarping of the jaw plate such that the working surface of the plate bowsoutwardly and the rear surface of the plate becomes a concave surface.In becoming a concave surface, the center portion of the rear surfacepulls away from the flat seat of the jaw against which it is meant to besecured.

Warping of the jaw plate in this manner puts a severe strain on thefastening bolts, frequently stretching them permanently, and the jawplate becomes deformed until only its vertical edges are in contact withthe flat jaw seat such that the middle portion of the plate is unevenlyor incompletely backed. When the jaw plate is supported only along itsedges it is equivalent to a beam supported only at its ends and, as acrushing force is applied to the plate each time the jaws move together,the jaw plate is subjected to repeated bending stresses which tend tocause the plate to crack due to fatigue failure. In one instance knownto the present inventor fatigue failure of this nature caused thedevelopment of a crack eighteen inches long and one and three-quartersinches wide.

An object of the present invention is to provide a new and improved jawplate which will not warp, bow or be appreciably deformed by repeatedimpacts against its working surface of the material being crushed.

A more specific object of the invention is to provide the workingsurface of a jaw plate with recesses into which cold worked metal of theworking surface may flow to prevent overall lateral expansion of theworking surface.

The above and other objects and advantages appearing herein may becarried into practical effect in the manner described hereinbelow,reference being made to the accompanying drawing in which:

Fig. l is a cross sectional view taken through a jaw crusher having jawplates of the type in which the present invention may be embodied;

Fig. 2 is a broken sectional view of one of the jaw plates of Fig. 1,constructed in accordance with the present invention; and

Fig. 3 is a sectional view of a typical jaw plate that does not embodythe present invention. Superimposed thereon, in dotted lines, is theshape (exaggerated for the sake of illustration) the plate will assumeafter its working action referred to hereinabove.

The crusher illustrated in Fig. l is an ordinary jaw type crusher havinga stationary and a movable jaw each equipped with jaw plates of the typein which the present invention may be embodied. The frame 1 of thecrusher has a stationary jaw body 2. A movable or swinging jaw body 3 ispivoted to frame 1 at 4 and has a crushing movement imparted to it by acrusher toggle 6 ac-' tuated by a mechanism well known in the art andforming no part of the present invention.

Stationary jaw body 2 and swing jaw body 3 each have two jaw platereceiving surfaces or seats 7 which may or may not be formed onrenewable backing plates 8. Fastened on jaw bodies 2 and 3 are aplurality of heavy steel jaw plates 9 formed with their rear surfacesadapted to fit against suitably formed seats 7. Intermediate the cornersof each of the jaw plates 9' are formed one or more counterbore recessesfor receiving the heads of bolts 11, the shanks of which pass throughholes in jaw plates 9 and respectively through'holes in the jaw bodies 2and 3.

The foregoing structure is well known and part of the present invention.

With reference to Fig. 2, the present invention pertains to theproviding of working surface 15 of a jaw plate 9 with longitudinallyextending re-entrant recesses or grooves 16 into which cold worked metalof surface 15 may flow to prevent an overall lateral expansion of theworking surface. Working surface 15, as seen in section in Fig. 2,appears as a series of waves with the projections or crests 17 of eachof the waves extending longitudinally of the jaw plate 9. Juxtaposedcrests 17 are valley portions which provide working surface 15 with across sectional appearance similar to a conventional sign wave curve. Avalley portion, therefore, comprises a descending or negative slopesegment, an ascending or positive slope segment, and a bottom segment.The bottom segment corresponds analogously to the peak of the negativehalf cycle of the sign wave curve. One or more re-entrant recesses 16are formed in each of the valley portions of the working surface 15between crests 17, e. g., in Fig. 2 two re-entrant recesses 16, 16 aredisposed in a valley portion, one on the ascending slope segment and oneon the descending slope segment. Thus the working surface 15 isinterrupted by the gaps defined by recesses 16, 16. Recesses 16 as seenin Fig. 2, are defined in part by opposed spaced sidewall portions whichextend generally normal to and merge with working surface 15. When thesurface layer of each portion of working surface 15 expands laterallydue to cold working, the surface layer of metal flows so as to causerecesses 16 to close but an overall lateral expansion of working surface15 does not occur.

It is seen that by preventing an overall expansion of working surface15, the normal tendency of the jaw plate 9 to bow or become warped iseliminated. The rear surface 18 of the jaw plate therefore remains fiatinstead of assuming a concave shape as when the plate becomes bowed. Asa metal surface can be cold worked to the point where further impactingproduces no appreciable expansion in the surface, the dimensions ofgrooves 16 may be predetermined such that no further expansion of theworking surface, or portions thereof, will occur after the grooves areclosed.

The advantage of applicants invention in preventing an overall expansionof working surface 15 will be more fully understood from a discussion ofhow a jaw plate normally responds to cold working of its workingsurface. Fig. 3 shows a typical jaw plate in section which forms no 3does .not embody the grooves of the present invention. Superimposed indotted lines on the jaw plate in Fig. 3 is the shape, shown exaggeratedfor the sake of illustration, the plate will assume after its Workingsurface is :cold worked by the crushing impacts to which jaw plates arenormally-subjected.

It is well known that in the operation of a corrugated wear plate, thegreatest wear occurs at the ridges or crests, less wear occurs at thebottom segments of the valley portions, and the least wear Occurs at theslope segments.

Cold working of working surface 115 causes it to expand laterally inboth directions from line 120 (Fig. 3) and, as the actual length of rearsurface 118 is not lengthened correspondingly, the jaw plate becomesbowed such that rear surface 118 becomes a concave surface as indicatedby broken line 118' and working surface 115 bows :outwardly as indicatedby broken line 115. The undesirability of having the jaw plate bowoutwardly in this manner is .that the plate is supported only along itsedges leaving the middle portion of the plate unevenly or incompletelybacked. The plate will tend to flatten out each time .the jaws of thecrusher move together and the intermittent bending stresses willultimately cause the plate 'to crack due to fatigue failure.

Lateral expansion of the working surface as described above also causesplates 9 to expand laterally, as indicated in Fig. 3, such that theplates may ultimately contact the stationary sidewalls .of the crushingchamber. Thus, when one of the plates 9 on movable jaw 3 contacts thesidewalls in this manner, the swinging action of the jaw meets withcontinually increasing resistance and finally stops when such resistancebecomes too great to'be overcome.

It will be understood the particular embodiment of the inventiondescribed herein and illustrated in the drawing is exemplary only, andthe invention as applied to jaw plates for cnlshers is intended toinclude such modifications and equivalents as may readily occur topersons skilled in the art, the invention being limited only .by theterms of the appended claims.

It :is claimed and desired to secure by Letters Patent:

1. A wear plate for the working surface of a machine for crushingmaterial, said wear plate presenting a working surface having .aplurality of juxtapositioned valleys and ridges extending in thedirection of the flow of said material when said plate is in workingposition, a portion of said working surface which includesadjacent ridgeand valley surface areas being provided with an elongated recess whichalso extends in said direction of flow of material, said recess beingdefined in part by spaced opposed sidewall portions which are disposedgenerally normal to and merge with said ridge and valley surface areasof said portion of said working surface.

2. A wear plate for the working part of a machine for crushing material,said wear plate presenting a working surface having a plurality ofjuxtapositioned valleys and ridges extending in the direction of theflow of said material when said plate is in working position, saidworking face having adjoining ridge and valley portions thereof providedwith an elongated recess :which also extends in said direction of flowof material, said recess being defined in part by spaced opposedsidewall portions which are disposed generally normal to and merge withsaid ridge and valley portions of said working surface.

3. A wear plate for the Working part of a machine for crushing material,said wear plate presenting a working surface having a plurality ofjuxtapositioned valleys and ridges, said valleys and ridges extending inthe .direction of the flow of said material when said plate is inworking position, said wear plate further presenting a re-entrant recessdefined in part by spaced opposedsid'ewall portions extending generallynormal to said Working surface, said recess extending parallel ofsaidridges intermediate one of said ridges and the valley adjacent thereto.

4. A wear plate for the Working part of .a machine for crushingmaterial, said wear plate presenting a working surface having aplurality of juxtapositioned valleys and ridges, said valleys and ridgesextending in .the direction of the flow of .said material when saidplate is in working position, said wear plate further presenting .aplurality-of .re-entrant recesses, each of said recesses being definedin .part by spaced opposed sidewall portions'rextending generally normalto and merging with said working surface and extending parallel to .saidridges intermediate one of said ridges and the valley radjacentithereto.

References Cited in the file of this patent UNITED STATES PATENTS1,626,535 Hush Apr. 26, 1927 2,465,607 'Roubal Mar. 29, 1949 2,609,154Baker Sept. 2, 19.52

FOREIGN PATENTS 341 Great Britain Ian. 26, 1881 38,054 Switzerland Nov.'19, 1906 306,609 Great Britain 'Feb. 28, '1929

